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Podiceps Arndti
''Podiceps arndti'' is an extinct species of grebe from the Upper Pliocene of California. History The species was described in a monograph on fossil birds of the San Diego Formation from Robert M. Chandler in 1990. The species name "arndti" is in honor of Joseph Arndt for his contributions for the Natural History Museum of Los Angeles County with collecting fossils from the San Diego Formation. Description Specimens of ''Podiceps arndti'' consisted of several associated femura, tibiotarsi and tarsometatarsi. The species can be differentiated from other species of ''Podiceps'' in which the trochanteric ridge of the femur separated from the trochanter. The depression inside of the trochanteric ridge is more distal to the iliac surface than beside the ridge as well. The species is smaller than the red-necked grebe (''P. grisegena''), though it was larger than other species of contemporary grebes with only the later '' P. parvus'' being of similar size. Paleobiology ''P. arndti'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grebe
Grebes () are aquatic diving birds in the order (biology), order Podicipediformes (). Grebes are widely distributed freshwater birds, with some species also found in sea, marine habitats during Bird migration, migration and winter. Most grebes fly, although some flightless species exist, most notably in stable lakes. The order contains a single family (biology), family, the Podicipedidae, which includes 22 species in six extant genus, genera. Although, superficially, they resemble other diving birds such as loons and coots, they are most closely related to flamingos, as supported by morphology (biology), morphological, molecular and paleontology, paleontological data. Many species are monogamy in animals, monogamous and are known for their courtship displays, with the pair performing synchronized dances across the water's surface. The birds build floating vegetative nests where they lay several eggs. About a third of the world's grebes are listed at various levels of conservatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Diego Formation
The San Diego Formation is a geological formation in southwestern San Diego County, California, United States, and northwestern Baja California, Mexico. Geology It is a coastal transitional marine and non-marine pebble and cobble conglomerate deposit and marine sandstone rock with marine fossils, from a former bay, deposited during the Middle Pliocene to Late Pliocene ages (2–3 million years ago), of the Pliocene period during the Cenozoic Era. This formation is found from the south side of Mount Soledad in San Diego County to Rosarito Beach in northern Baja California, including Tijuana, Mexico, and the southwestern corner of San Diego County from San Ysidro to Pacific Beach. San Diego Formation deposits were formed in a large, open, crescent-shaped bay similar in size to Monterey Bay that existed on the coast in Pliocene times. Aquifer The formation contains the San Diego Formation Basin, a large aquifer under Imperial Beach, Chula Vista, National City, and souther ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural History Museum Of Los Angeles County
Nature is an inherent character or constitution, particularly of the ecosphere or the universe as a whole. In this general sense nature refers to the laws, elements and phenomena of the physical world, including life. Although humans are part of nature, human activity or humans as a whole are often described as at times at odds, or outright separate and even superior to nature. During the advent of modern scientific method in the last several centuries, nature became the passive reality, organized and moved by divine laws. With the Industrial Revolution, nature increasingly became seen as the part of reality deprived from intentional intervention: it was hence considered as sacred by some traditions ( Rousseau, American transcendentalism) or a mere decorum for divine providence or human history ( Hegel, Marx). However, a vitalist vision of nature, closer to the pre-Socratic one, got reborn at the same time, especially after Charles Darwin. Within the various uses of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Femur
The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femoral head, top of the femur fits into a socket in the pelvis called the hip joint, and the bottom of the femur connects to the shinbone (tibia) and kneecap (patella) to form the knee. In humans the femur is the largest and thickest bone in the body. Structure The femur is the only bone in the upper Human leg, leg. The two femurs converge Anatomical terms of location, medially toward the knees, where they articulate with the Anatomical terms of location, proximal ends of the tibiae. The angle at which the femora converge is an important factor in determining the femoral-tibial angle. In females, thicker pelvic bones cause the femora to converge more than in males. In the condition genu valgum, ''genu valgum'' (knock knee), the femurs conve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tibiotarsus
The tibiotarsus is the large bone between the femur and the tarsometatarsus in the leg of a bird. It is the fusion of the proximal part of the tarsus with the tibia. A similar structure also occurred in the Mesozoic Heterodontosauridae. These small ornithischian dinosaurs were unrelated to birds and the similarity of their foot bones is best explained by convergent evolution. See also * Bird anatomy References * Proctor, Nobel S. ''Manual of Ornithology: Avian Structure and Function''. Yale University Press Yale University Press is the university press of Yale University. It was founded in 1908 by George Parmly Day and Clarence Day, grandsons of Benjamin Day, and became a department of Yale University in 1961, but it remains financially and ope .... (1993) Bird anatomy Dinosaur anatomy {{ornithology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tarsometatarsus
The tarsometatarsus is a bone that is only found in the lower leg of birds and some non-avian dinosaurs. It is formed from the fusion of several bird bones found in other types of animals, and homologous to the mammalian tarsus (ankle bones) and metatarsal bones (foot). Despite this, the tarsometatarsus of flying types is often referred to as just the shank, tarsus or metatarsus. Tarsometatarsal fusion occurred in several ways and extents throughout bird evolution. Paticularly, in Neornithes (modern birds), although the bones are joined along their entire length, the fusion is most thorough at the distal (metatarsal) end. In the Enantiornithes, a group of Mesozoic avialans, the fusion was complete at the proximal (tarsal) end, but the distal metatarsi were still partially distinct. While these fused bones are best known from birds and their relatives, avians are neither the only group nor the first to possess tarsometatarsi. In a remarkable case of parallel evolution, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Podiceps
''Podiceps'' is a genus of birds in the grebe family. The genus name comes from Latin , "rear-end" and ', "foot", and is a reference to the placement of a grebe's legs towards the rear of its body. It has representatives breeding in all continents except Antarctica. Some species are partially or entirely migratory, moving in winter to the coast or warmer climates. Most species are widespread and overall common, but three South American species each are restricted to a single country; two of them are seriously threatened and a third is already extinct. They breed in vegetated areas of freshwater lakes, nesting on the water's edge, since their legs are set too far back for easy walking. Usually two eggs are laid, and the striped young may be carried on the adult's back. All the genus are excellent swimmers and divers, and pursue their fish prey underwater. Adults have striking breeding plumage, with no difference between the sexes. In winter, the plumage is subdued whites and gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trochanter
A trochanter is a tubercle of the femur near its joint with the hip bone. In humans and most mammals, the trochanters serve as important muscle attachment sites. Humans have two, sometimes three, trochanters. Etymology The anatomical term ''trochanter'' (the bony protrusions on the femur) derives from the Greek τροχαντήρ (''trochantḗr''). This Greek word itself is generally broken down into: * τροχάζω (''trokházō''), meaning “to run quickly,” “to gallop,” or “to move rapidly.” * -τήρ (''-tḗr''), a suffix in Greek that often signifies an agent or instrument (“one who oes something or “that which oes something). While the exact origin of the anatomical term trochanter is uncertain, multiple possible connections could be suggested. One possibility is that the term was derived directly from the Greek roots without influence from the maritime meaning, with the name referencing the trochanter’s role in enabling swift movement throu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ilium (bone)
The ilium () (: ilia) is the uppermost and largest region of the coxal bone, and appears in most vertebrates including mammals and birds, but not bony fish. All reptiles have an ilium except snakes, with the exception of some snake species which have a tiny bone considered to be an ilium. The ilium of the human is divisible into two parts, the body and the wing; the separation is indicated on the top surface by a curved line, the arcuate line, and on the external surface by the margin of the acetabulum. The name comes from the Latin ('' ile'', ''ilis''), meaning "groin" or "flank". Structure The ilium consists of the body and wing. Together with the ischium and pubis, to which the ilium is connected, these form the pelvic bone, with only a faint line indicating the place of union. The body () forms less than two-fifths of the acetabulum; and also forms part of the acetabular fossa. The internal surface of the body is part of the wall of the lesser pelvis and gives o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red-necked Grebe
The red-necked grebe (''Podiceps grisegena'') is a migratory aquatic bird found in the temperate regions of the northern hemisphere. Its wintering habitat is largely restricted to calm waters just beyond the waves around ocean coasts, although some birds may winter on large lakes. Grebes prefer shallow bodies of fresh water such as lakes, marshes or fish-ponds as breeding sites. The red-necked grebe is a fairly drab dusky-grey bird in winter. During the breeding season, it acquires the distinctive red neck plumage, black cap and contrasting pale grey face from which its name was derived. It also has an elaborate courtship display and a variety of loud mating calls. Once paired, it builds a nest from water plants on top of floating vegetation in a shallow lake or bog. Like all grebes, the red-necked is a good swimmer and particularly swift diver, and responds to danger by diving rather than flying. The feet are positioned far back on the body, near the tail, which makes the bi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Podiceps Parvus
''Podiceps parvus'' was a grebe in the genus ''Podiceps'' native to the North America. It went extinct in late Pleistocene. First described by Robert W. Shufeldt in 1913. Distribution and age range ''Podiceps parvus'' fossils were found in Mexico and western USA (Oregon, California). Earliest recovered parts are dated back 3.6 million years ago. Latest ones - about 11,700 years ago. Ecology and characteristics Unknown. It was a carnivore, its diet likely contained invertebrates and small vertebrates. Material collected from Fossil Lake in 2010 was studied. The ulna had a maximum length of 91.15 mm and carpometacarpus 40.65 mm. References parvus Alexander Lvovich Parvus, born Israel Lazarevich Gelfand (8 September 1867 – 12 December 1924) and sometimes called Helphand in the literature on the Russian Revolution, was a Marxist theoretician, publicist, and controversial activist in the ... Birds of Mexico Prehistoric birds of North America Fossil taxa described ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piacenzian
The Piacenzian is in the international geologic time scale the upper stage (stratigraphy), stage or latest age (geology), age of the Pliocene. It spans the time between 3.6 ± 0.005 year#SI prefix multipliers, Ma and 2.58 Ma (million years ago). The Piacenzian is after the Zanclean and is followed by the Gelasian (part of the Pleistocene). The Piacenzian is roughly coeval with the European land mammal age MN 16, overlaps the late Chapadmalalan and early Uquian South American land mammal age and falls inside the more extensive Blancan North American land mammal age. It also correlates with the Astian, Redonian, Reuverian and Romanian regional stages of Europe, and the Waipipian and Mangapanian stages of New Zealand geologic time scale, New Zealand. Some authorities describe the British Red Crag Formation and Waltonian Stage as late Piacenzian, while others regard them as early Pleistocene. Carbon dioxide levels during the Piacenzian were similar to those of today, making this age, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
